A beach clean on Isle of Eigg, Scotland. Some 20% of the litter was packaging from single-use plastic items.
Photograph: Will Rose/Greenpeace

The rubbish washing up on the UK’s beaches is continuing to increase, rising by 10% in 2017, the Marine Conservation Society’s (MCS) annual beach clean has revealed.

Much of the waste is plastic, leading the MCS to call on the government to urgently introduce a charge on single-use plastic items, such as straws, cups and cutlery. The chancellor, Philip Hammond, recently announced the government is considering such action.

About 12m tonnes of plastic litter enters the oceans every year, killing millions of marine animals. People are also believed to be inadvertently eating the plastic, potentially contaminated with toxic chemicals, via seafood.

The MCS beach clean in September saw 7,000 volunteers scour 340 beaches and collect an average of 718 pieces of rubbish every 100 metres. The survey uses a standard methodology and data from the last decade and shows a rising tide of litter along the coast.

Most of the litter is small, unidentifiable fragments of plastic, broken down in the sea from larger objects and often mistaken for food by fish and birds. But 20% of the rubbish is packaging from “on the go” food and drink, such as cups, bottles, cutlery, stirrers and sandwich packets.

“Our beach clean evidence shows a shocking rise in the amount of litter this year,” said Sandy Luk, MCS chief executive. “Our oceans are choking in plastic. We urgently need a levy on single-use plastic as a first step.”

“We are concerned we are continuing on this upwards trend,” said Lizzie Prior, beach and river clean project officer at the MCS. “Plastic never goes away – it does not decompose. It just goes to smaller and smaller pieces and becomes much more harmful for our marine environment.”

She said the tax on plastic bags introduced in 2015, which has seen their use drop by 85%, had a rapid impact, with the number of bags found on beaches down by 40% since 2014. “It is really fantastic to see that small charge completely changed people’s behaviour,” she said. “A levy [on other single use plastic] would be a fantastic next step.”

The populous south-east of England had the highest amount of litter, with 1,092 items per 100 metres of beach, a jump of 46% from last year. South-west England was second, with 1,036 items per 100 metres.

A spokesman for the Department of Environment, Food and Rural Affairs said: “We are taking significant steps to tackle plastic waste including plans to introduce a ban on plastic microbeads and a call for evidence around deposit reward and return schemes for plastic bottles. We recognise there is more to do in this area, and we will be working with industry to explore how we can further reduce the amount of single-use plastic waste.”

The MCS 2017 survey found the second highest amount of litter in the 10 years for which there is comparable data. The peak in 2014 is thought likely to be the result of unusually severe storms early that year, which washed up more rubbish.

The MCS also found a big leap in wet wipes litter in 2017, up 94% on the previous year, though the cause is unclear. Most wet wipes contain plastic and Prior said she knew of no wet wipes on sale today that meet water company standards for degradability.

She said people should not flush them down the toilet and that labelling on wet wipes needs to improve: “If they don’t meet the water company standards, they should say ‘non-flushable’ very clearly on the front of the packet.”

Prior said only three things should be flushed down toilets: “If you remember the three Ps – pee, poo and paper – you’re doing the right thing.”